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LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
DESCRIPTION
The LX3005 also features an enable
function, internal circuitry for soft start,
and protection schemes such as thermal
shutdown, over-current protection, and
short-circuit protection. When OCP or
SCP is triggered, the device operating
frequency will be reduced from typically
420kHz to typically 40kHz, limiting the
output power capability.
The LX3005 serves as an ideal power
supply device for portable devices,
especially for chipset power in portable
systems. It’s widely used for PDVD, LCD
monitor and DPF chipset power sources.
The LX3005 is available in SOIC8
package and is functional from an ambient
temperature range of 0˚C to 85˚C.
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•
•
•
•
•
•
•
•
2A Constant Output Current
130mΩ RDSON Internal Power MOSFET
Up to 94% Efficiency
Fixed 420kHz Frequency
Wide 4.75V to 25V Input Voltage Range
Output Voltage Adjustable from 0.8V to
21V
Built-in Thermal Shutdown Function
Built-in Current Limit Function
Built-in Soft-start Function
Support Ceramic or Electrolytic
Capacitors
Pb-free and RoHS Compliant
WWW . Microsemi .C OM
The LX3005 is a 420kHz fixed
frequency PWM buck (step-down) DC-DC
converter, capable of driving a 2A load
with high efficiency, low ripple and
excellent line and load regulation. The
device operates over a wide input voltage
range of 4.75V to 25V, and the output
voltage can be externally set from 0.8V to
a voltage near VIN, as the PWM control
circuit is able to adjust the duty ratio
linearly from 0% to close to 100%.
The LX3005 device integrates a
high-side low RDSON PMOS for a low
cost and high efficiency solution. An
internal transconductance error amplifier
is used in the control loop allowing
flexibility to compensate the system using
an all ceramic capacitor system.
KEY FEATURES
APPLICATIONS
•
•
•
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Portable DVD
LCD Monitor/LCD TV
Digital Photo Frame
ADSL
Set-Top Box
IMPORTANT: : For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Patents Pending
PRODUCT HIGHLIGHT
VIN
VIN
SW
EN
ON OFF
LX3005
CIN
RC
D1
GND
0 to 85
DM
CO
R1
THERMAL DATA
Plastic SOIC 8-pin
θJA = 100°C/W
RoHS Compliant / Pb-free
THERMAL RESISTANCE-JUNCTION TO AMBIENT
LX3005CDM
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the
device/pc-board system. All of the above assume no ambient airflow.
Note: Available in Tape & Reel. Append the letters “TR” to the part number.
(i.e. LX3005CDM-TR)
Copyright © 2010
Rev.1.0, 2010-02-05
R2
LX3005
PACKAGE ORDER INFO
TA (°C)
C1
FB
COMP
CC
VOUT @ 2A
L1
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 1
LX3005
®
TM
2A STEP-DOWN CONVERTER
P RODUCTION D ATASHEET
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
1
VIN
2
SW
3
GND
4
8
NC
7
EN
6
COMP
5
FB
DM PACKAGE
(Top View)
xxxx = date/lot code
RoHS / Pb-free 100% Matte Tin Pin Finish
WWW . Microsemi .C OM
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
NC
MSC
3005CDM
xxxx
Supply Input Voltage (VIN)................................................................-0.3V to 30V
FB Pin Voltage (VFB)...........................................................................-0.3V to 6V
EN Pin Voltage (VEN)......................................................................... -0.3V to VIN
COMP Pin Voltage (VCOMP) ................................................................-0.3V to 6V
SW Pin Voltage (VSW)........................................................................ -0.3V to VIN
Power Dissipation (PD) ............................................................... Internally limited
Maximum Operating Junction Temperature.................................................150°C
Storage Temperature Range .......................................................... -65°C to 150°C
Lead Temperature (Soldering, 10 seconds) ..................................................260°C
FUNCTIONAL PIN DESCRIPTION
Name
Pin #
Description
NC
1
Pin not used.
VIN
2
Supply Voltage Pin. The LX3005 operates from a 4.75V to 25V DC voltage. Bypass VIN to GND
with a suitable large capacitor to eliminate noise on the input.
SW
3
Power Switch Output Pin. SW is the switch node that supplies power to the output.
GND
4
Ground for IC.
FB
5
Feedback Pin. Through an external resistor divider network, FB senses the output voltage and
regulates it. To prevent current limit run away in a short circuit fault condition, the frequency
feedback comparator lowers the oscillator frequency to 40kHz when the FB voltage is below
0.52V. The feedback threshold voltage is 0.8V.
COMP
6
Compensation Pin. This pin is the output of the error amplifier. Frequency compensation is done
at this pin by connecting a series RC to ground(parallel a capacitor if necessary)
EN
7
Enable Pin. Drive EN pin high to turn on the device, drive it low to turn off. Default of this pin is
high level.
NC
8
Pin not used.
LX3005
Copyright © 2010
Rev.1.0, 2010-02-05
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 2
LX3005
®
TM
2A STEP-DOWN CONVERTER
P RODUCTION D ATASHEET
ELECTRICAL CHARACTERISTICS
Parameter
Symbol
Test Conditions / Comment
Min
Typ
Max
Units
25
V
VIN
Recommended Voltage Range
VIN
Shut-Down Quiescent Current
ISHDN
Operating Quiescent Current
IQ
4.75
VEN = 0.4V
44
60
µA
VEN = 2V, VFB = 1.3V
1.3
2
mA
ENABLE
EN Pin Threshold
EN Pin Input Leakage Current
VH
1.5
VL
0.7
IFB
VEN = 2.5V
Internal FB Voltage
VFB
VIN = 5V to 25V
Input Bias Current
IFB
VFB = 1.3V
V
-5
-10
µA
0.8
0.816
V
-0.1
-0.5
µA
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Unless otherwise listed, the following specifications at the operating ambient temperature 25°C and VIN = 12V, VOUT = 5V.
FB VOLTAGE
0.784
ERROR AMP
Error Amplifier Voltage Gain
GV
1000
V/V
Error Amplifier
Transconductance
GS
700
µA/V
OSCILLATOR
Operating Frequency
fOSC
336
420
504
kHz
130
150
ohm
100
%
HIGH SIDE DRIVER
Internal PMOS ON Resistance
RDSON
VFB = 065V, VEN = 12V, IOUT = 2A, TC = 25°C
Maximum Duty Cycle
DMAX
VFB = 0.65V, ISW = 0.1A
CURRENT LIMIT
Switch Current Limit
ILIM
Frequency of Current Limit or
Short Circuit Protection
GS
TC = 25°C
2.5
3.4
A
40
kHz
155
°C
20
°C
THERMAL SHUTDOWN
Threshold
TOTSD
Hysteresis
THYS
NOTE1
NOTE1: This parameter is guaranteed by design but not tested in production (GBNT).
LX3005
Copyright © 2010
Rev.1.0, 2010-02-05
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 3
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
FUNCTIONAL BLOCK DIAGRAM
WWW . Microsemi .C OM
EN
VIN
Soft-start
Bias
Generator
+
UVLO
OCP
-
BG Ref
800mV
+
EA
FB
+
-
PWM
Driver
Latch
-
SW
OTP
420kHz/40kHz
Clock and Ramp
+
OSP
0.52V
GND
-
COMP
Figure 1. Block Diagram
TYPICAL APPLICATION
12V
ON OFF
CIN
22µF
25V
8
2
VIN
L1 22µH
SW
EN
3
C1
100pF
LX3005CMD
CC 10nF
6
RC 8.2k
COMP
FB
5V/2A
R2
107k
5
D1
DFLS230L
30V 2A
R1
20k
LX3005
GND
4
CO
22µF
16V
COPTIONAL
Figure 2. VIN = 12V, VOUT = 5V, Ceramic Capacitors Input & Output
Copyright © 2010
Rev.1.0, 2010-02-05
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 4
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
TYPICAL APPLICATION
ON OFF
CIN
100µF
25V
8
2
VIN
L1 22µH
SW
EN
3
C1
100pF
LX3005CMD
CC 10nF
6
COMP
RC 8.2k
FB
5V/2A
R2
107k
5
D1
DFLS230L
30V 2A
GND
4
CO
100µF
16V
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12V
R1
20k
COPTIONAL
Figure 3. VIN = 12V, VOUT = 5V, Electrolytic Capacitors Input & Output
OUTPUT RIPPLE 2A LOAD
OUTPUT RIPPLE DISCONTINOUS MODE
Copyright © 2010
Rev.1.0, 2010-02-05
VIN = 12V, VOUT = 5V, IOUT = 50mA
22uF ceramic output capacitors and a 22μH inductor
Channel 1 – Switch Node
Channel 2 – VOUT AC Coupled
Channel 3 – VOUT
Channel 4 – Inductor Current
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 5
LX3005
VIN = 12V, VOUT = 5V, IOUT = 2A, 10mVpp
22uF Ceramic Output Capacitor and a 22μH Inductor
Channel 1 – Switch Node
Channel 2 – VOUT AC Coupled
Channel 3 – VOUT
Channel 4 – Inductor Current
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
CASE TEMPERATURE VS IOUT & VOUT
CASE TEMPERATURE VS VIN & IOUT
90
90
VOU T = 5 V
V OU T = 2 A
VOU T =
3.3V
Case Temperature (°C)
Case Temperature (°C)
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80
70
60
50
40
80
70
60
V OU T = 1A
50
30
VIN - 12V
40
8
20
0.2
0.6
Output1
Current
1.4
(A)
12
16
20
24
Input Voltge (V)
1.8
OUTPUT VOLTAGE V OUTPUT CURRENT
FB VOLTAGE VS TEMPERATURE
5.2 0
0.804
5.10
0.802
FB Voltage (V)
Output Voltage (V)
5. 15
5. 0 5
5.0 0
4 .9 5
4 .9 0
0.800
0.798
4 .8 5
0.796
4 .8 0
0
0 .4
0 .8
1.2
1.6
2
2 .4
-40
0
Output Current (A)
80
120
OP & OCP FREQUENCY VS TEMPERATURE
MAXIMUM IOUT VS INPUT VOLTAGE
2 .75
500
Operation Frequency (kHz)
Operating Frequency
2 .2 5
1.75
1. 2 5
V O UT = 2 .5
V O UT = 3 .3 V
0 .75
OCP Frequency * 10
450
400
LX3005
Maximum Output Current (A)
40
Junction Temperature (°C)
350
V O UT = 5 V
300
0 .2 5
0
5
10
15
20
25
Input Voltage (V)
Copyright © 2010
Rev.1.0, 2010-02-05
-40
0
40
80
120
Junction Temperature (°C)
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 6
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
SUPPLY QUIESCENT CURRENT
SHUTDOWN QUIESCENT CURRENT
Shutdown Quiescent Current (uA)
100
2
1.6
1.2
T J = 125°C
0.8
T J = 75°C
T J = 25°C
T J = - 50°C
80
60
40
TJ = 125°C
20
TJ = 75°C
TJ = 25°C
TJ = -50°C
0
0.4
4
8
12
16
20
24
4
8
12
Input Voltage (V)
20
24
OCP CURRENT LIMIT VS INPUT SUPPLY
5
OCP Current Limit (A)
5
OCP Current Limit (A)
16
Input Voltage (V)
OCP CURRENT LIMIT VS TEMPERATURE
4
3
2
VIN = 12V
1
-40
4
3
2
1
0
40
80
120
4
8
12
Junction Tem perature (°C)
16
20
24
Input Voltge (V)
EFFICIENCY VS VOUT & IOUT
EFFICIENCY VS VIN & IOUT
94
10 0
V OU T = 5V
90
V OU T = 3 . 3 V
86
Efficiency (%)
95
V OU T = 1A
LX3005
Efficiency (%)
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Supply Quiescent Current (mA)
2.4
90
V O U T = 2 .5V
V OU T = 2 A
85
82
VIN - 12V
80
78
0 .4
0 .8
1. 2
1. 6
8
2
Output Current (A)
Copyright © 2010
Rev.1.0, 2010-02-05
12
16
20
24
Input Supply (V)
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 7
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
APPLICATION INFORMATION
OUTPUT CAPACITOR SELECTION
To set the output voltage, connect a resistive divider from
the output to the FB pin to signal ground. Note that the
feedback voltage is 0.8V. For the desired output voltage
VOUT, R2 is calculated by the following equation:
The output capacitor value is basically decided by the
amount of the output voltage ripple allowed during the
steady state (DC) load condition as well as the load
transient response requirement. The optimum design may
require a couple of iterations to satisfy both conditions.
⎛ VOUT ⎞
− 1⎟
⎝ VFB
⎠
R 2 = R1 × ⎜
R1 is selected to be 10kΩ to 20kΩ and VFB=0.8V. Refer
to Figure 2 or Figure 3.
V
= ESR × I
RIPPLE
RIPPLE
OUTPUT INDUCTOR SELECTION
The value of inductor is decided by the input and output
voltage, inductor ripple current and operating frequency.
A larger inductor value means smaller ripple current.
However if the inductance is chosen too large, it results in
a slower response and possibly lower efficiency if the
losses from the increased DCR outweigh the losses
eliminated from a smaller ripple current. Likewise, a
smaller inductor reduces the inductor size and cost,
improves large signal response, but increases inductor
ripple current which leads to lower efficiency and also an
increase output ripple voltage. The magnitude of ripple
current is a design freedom which can be decided by the
design engineer according to various application
requirements. The inductor value can be calculated by
using the following equations:
L=
(VIN − VOUT ) × VOUT
VIN × FS × k × I LOAD
⎛ I
⎞
RIPPLE ⎟
V
= ESR × I
+⎜
RIPPLE
RIPPLE ⎜ 8 × C
×F ⎟
OUT S ⎠
⎝
COUT is the output capacitance used, and FS is the switching
frequency.
The desirable output voltage change during a load transient
dictates the output capacitance requirement. For a given
output voltage change ΔVOUT, the output capacitance can
be calculated by:
2
ΔI
⎞
⎛
L × ⎜ I LOAD + LOAD ⎟
2 ⎠
⎝
COUT =
(ΔVOUT + VOUT )2 − VOUT 2
Based on the desired output ripple voltage and output
voltage deviation during load transients, the output
capacitance and its ESR can be approximated by the
equations listed above.
The inductor ripple current can be calculated by:
(VIN − VOUT ) × VOUT
INPUT CAPACITOR SELECTION
VIN × FS × L
A good design rule is to choose the inductor value such
that k=0.3, which means that the inductor ripple current is
30% of the nominal output load current.
Input capacitors are usually a mix of high frequency
ceramic capacitors and bulk capacitors. Ceramic capacitors
bypass the high frequency noise, and bulk capacitors
supply switching current to the MOSFET while keeping
the DC input voltage steady. Usually a 1μF ceramic
capacitor is chosen to decouple the high frequency noise.
The bulk input capacitor is selected to support the input
voltage rating and input RMS current rating, and can be a
ceramic type.
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 8
LX3005
Where FS is the switching frequency (420kHz), ILOAD is
the output load current; k is percentage of output current.
Copyright © 2010
Rev.1.0, 2010-02-05
However, if ceramic capacitors are used, the output ripple
voltage is a combination of both the ESR and the capacitor
charge and discharge, and can be approximated by:
Where ΔILOAD is the amount of change in the load current.
I RIPPLE = k × I LOAD
I RIPPLE =
The output ripple voltage is due to the ESR of the output
capacitor and the output capacitor charge and discharge.
For aluminum electrolytic capacitors, the output ripple is
largely caused by the capacitor ESR, where the output
ripple is:
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SETTING THE OUTPUT VOLTAGE
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
DEVICE POWER DISSIPATION
COMPENSATION
(
T =T + P
×θ
TOTAL
JA
J
A
)
The total power dissipated by the LX3005 device, PTOTAL, is
comprised of the power dissipated by the RMS current
flowing through the internal high-side FET, the switching
or transitioning of the FET, and the power dissipated by the
device quiescent supply current
The power dissipated due to the RMS input current flowing
through the high side FET during the ON time is:
P
=I
× RDS
RDSON
RMS
ON
2⎞
⎛
I
⎜
⎟
2
RIPPLE
IRMS = D⎜ IOUT +
⎟
12
⎜
⎟
⎝
⎠
The power dissipated during the switching or transition of
the internal FET is:
PSW =
VIN × IOUT × ( t R + t F )
× FS
4
Where tR and tF are the rise and fall time of the switch node
or the internal FET source node.
Finally, the power dissipated due to the device switching
supply current is:
P = VIN × IQ
IQ
where IQ, the device supply current when the device is
switching, can be approximated by the device’s supply
quiescent current.
The total power dissipated by the device is therefore:
P
=P
+P
+P
TOTAL
RDSON
SW IQ
Copyright © 2010
Rev.1.0, 2010-02-05
The LX3005 incorporates a transconductance amplifier in
its feedback control path. The inverting input to the
amplifier is at the FB pin, and the output of the amplifier at
the COMP pin. For compensating the device, a simple
zero – pole pair can be used if the frequency of the zero
created by the output capacitor and its ESR is lower than
the chosen unity gain cross-over frequency FC. This is
known as Type II compensation. See Figure 2. If the zero
of the output capacitor is located above the cross-over
frequency FC, as with ceramic capacitors that have very
low ESR, use a 2 zero 2 pole compensation, or a Type III
compensation network. For the LX3005, set the cross-over
frequency to be approximately 20kHz to 40kHz.
TYPE II COMPENSATION
If the output capacitor zero is located below the cross-over
frequency, use the following procedure for Type II
compensation. The following is an explanation of how to
design a TYPE II compensation network for the LX3005
converter:
Estimate the LC output filter double pole and zero:
f
f
LC
=
ZESR
1
2π L × COUT
=
1
2π × ESR × COUT
Next, select the cross-over frequency of the closed loop
bandwidth to be 40kHz or below.
In order for the overall closed loop bandwidth to cross over
at the desired frequency FC, the gain of the error or
transconductance amplifier should be adjusted such that at
the cross-over frequency FC, the product of the error
amplifier gain and the gain of the feed-forward modulator
path equals to 1.
The feed-forward modulator gain
consists of the internal PWM modulator gain, the LC
output filter response, and the external resistive divider
gain. This feed-forward modulator response can be
approximated by the following equation:
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 9
LX3005
Based on the device total power dissipation, the ambient
temperature, thermal resistance θJA, the device junction
temperature can be determined.
The LX3005 uses external compensation components that
allow for flexibility in designing the converter, since the
compensation can be optimized after the output filter
components (i.e. inductor and output capacitor) are
selected for the required application. Normally for low
cost applications, electrolytic capacitors that have high
ESR are used. For applications where board space is
critical, ceramics capacitors which have very low ESR are
used.
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The LX3005 will enter thermal shutdown when the die
temperature reaches close to 150˚C. The device junction
temperature is a function of the device’s total power
dissipation, the junction to ambient thermal resistance, and
the ambient temperature:
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
APPLICATION INFORMATION
G
MOD
=
VIN
VFB
ESR
×
VOUT 2π × F × L
C
(
TYPE III COMPENSATION
)
The gain of the transconductance amplifier near the cross
over frequency is:
G
EA
= gm × R
C
The product of the modulator gain and error amplifier gain
should equal to 1 at the cross-over frequency. Thus,
GMODxGEA = 1 and solve for RC.
V
× VOUT × 2π × F × L
C
, where VRAMP≈1.2V.
R = RAMP
C
gm × VIN × VFB × ESR
Type II compensation places a zero at or below the
frequency of the LC double pole, and a high frequency pole
at ½ the switching frequency or lower. The zero is created
by RC and CC while the pole is from RC and COPTIONAL. See
Figure 2.
Where f =
Z
1
1
and fp =
2π × R C × CC
2π × R C × COPT
LC
≥
1
2π × C × R
C
C
A cost effective method minimizing the number of
compensation components is to directly place a second
zero fZ2, at the frequency of the double pole. This zero is
created by R2 and C1 as shown in Figure 2.
f
LC
1
and solve for C1. Note that in this case,
2π × C × R
1
2
the second zero is added by C1 and R2 in addition to the
zero already introduced by RC and CC and also the pole
from RC and COPT as defined in Type II compensation.
The following are general but good practices for PCB
layout to prevent noise related issues, and achieve stable
operation of the converter:
1) Place all filtering capacitors as close to the IC as
possible. Use a power ground plane for the input
(CIN) and output (COUT) capacitors. All other
capacitors such as for compensation should use
signal ground.
= f , with RC and fLC, solve for CC
Z
Place a pole at high frequency at or below ½ the switch
frequency, and solve for COPT.
2) While having separate power ground and signal
ground planes, the two grounds should be
connected at one common point near the input
bypass capacitor ground.
1
1
×F ≥
=f
P
2 S 2π × C
×R
OPT
C
Note that the high frequency pole is optional. The purpose
of the high frequency pole is to close or attenuate the
overall loop response rejecting high frequency noise. If the
high frequency pole is not used, the overall loop at high
frequency will be determined by the high frequency
response of the error amplifier.
3) Make high current traces short and wide. This
includes the input current path and the inductor
current path. Minimize the loop path that consist
of the switch node (SW), the output filter
components, and the input capacitor.
4) Keep the switch node (SW), which is noisy, away
from sensitive analog paths to prevent noise
coupling onto sensitive signals such as at FB and
COMP pins.
F
f
C = P =5
f
F
Z
C
However, while satisfying this condition, it is important that
the zero is placed at or below the double frequency pole to
ensure stability.
5) Place all compensation components and feedback
resistors as close to the IC as possible, minimizing
trace lengths.
Note that a LX3005 evaluation board or demo board is
available. Please contact the factory for availability.
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 10
LX3005
A good rule of thumb in terms of placing the zero-pole pair
for approximately 60 degrees phase margin is to satisfy the
following condition:
Copyright © 2010
Rev.1.0, 2010-02-05
=
GENERAL LAYOUT GUIDELINES
Based on the calculated RC value, we can solve for CC such
that the zero is placed at or below the double pole
frequency.
f
When using low ESR ceramic output capacitors, the
frequency of the zero produced by the output capacitor is
usually above the cross-over frequency. In this case Type
III compensation should be used. In traditional Type III
compensation, two zeros and two poles, in addition to the
pole at the origin, are introduced by the error amplifier, and
the overall amplifier response is set via a feedback network
from the COMP output to the non-inverting input FB.
WWW . Microsemi .C OM
V
RAMP
×
LX3005
2A STEP-DOWN CONVERTER
®
TM
P RODUCTION D ATASHEET
PACKAGE DIMENSIONS
WWW . Microsemi .C OM
DM
8-Pin Plastic SOIC
Dim
A
A1
A2
b
c
D
E
e
H
L
θ
*LC
D
E
H
e
A2
A
A1
b
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.30
1.25
1.45
0.33
0.51
0.19
0.25
4.70
5.10
5.79
6.20
1.27 BSC
3.80
4.01
0.40
1.27
0
INCHES
MIN
MAX
0.053 0.069
0.004 0.012
0.049 0.057
0.013 0.020
0.007 0.010
0.185 0.201
0.228 0.244
0.050 BSC
0.150 0.158
0.016 0.050
8
.010
0
8
0.004
*Lead Coplanarity
c
Note:
L
1. Controlled dimensions are in mm, inches are for
reference only.
2. Dimensions do not include mold flash or protrusions;
these shall not exceed 0.155mm (.006”) on any side.
Lead dimension shall not include solder coverage.
LX3005
PRODUCTION DATA – Information contained in this document is proprietary to
Microsemi and is current as of publication date. This document may not be modified in
any way without the express written consent of Microsemi. Product processing does not
necessarily include testing of all parameters. Microsemi reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
Copyright © 2010
Rev.1.0, 2010-02-05
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 800-8776458, 714-898-8121, Fax: 714-893-2570
Page 11